The invention relates generally to air conditioning systems and, more particularly, to a cooling coil and method of manufacture.
In large air conditioning systems, commonly referred to as chiller systems, a liquid such as water or brine is circulated through an evaporator or cooler to chill liquid which is then passed through a heat exchanger of an air handler to cool the air that is then passed through the ductwork to cool spaces in the building. A fan in the air handler normally functions to draw the return air through the heat exchanger and discharge it out into the ductwork.
The cooling coil of the air handler is commonly of the plate fin type, wherein the longitudinally stacked plate fins have a plurality of rows of tubes that carry the cooling liquid, and the air is drawn transversely across the rows while giving up heat to the plate fins, which heat is then conducted to the tubes and hence to the cooling liquid. In the process, condensation is formed on the coil, and as it collects it tends to run down the coil and fall to a drain pan from which it can be properly disposed.
It has long been recognized that if the face velocity (i.e. the velocity of the air passing through the coil) is too great, it will tend to carry over the condensate into the fan and into the ductwork. This can result in leaks to the spaces to be cooled and possible corrosion of the ductwork. If, however, the face velocity is maintained at a moderate level, the condensate forming on the plate fins tends to be blown to the trailing edge of the coil where it then runs down the rear face of the coil to be collected in the drain pan.
One of the ways in which the costs associated with the manufacture of cooling coils can be reduced is that of reducing plate fin material and its associated casing material. As the fin and coil size is reduced, the rows of tubes become closer. Since the normal approach for making individual plate fins from a large sheet of material is to cut the material at a point midway between two rows of tube holes, the "close-row" coils also result in less material at both the leading and trailing edges of the plate fins. That is, both the leading edge and the trailing edge will be closer to the tube rows. The Applicants have recognized that as this space is reduced at the trailing edge, there is a greater tendency for the condensate to be blown off the trailing edge and to be carried over into the airstream.
It is therefore an object of the present invention to provide an improved coil structure and method of manufacture.
Another object of the present invention is the provision in the cooling coil for reducing the carry-over of condensate into the airflow stream.
Yet another object of the present invention is the provision in a close-row cooling coil for reduced blow off of condensate.
Yet another object of the present invention is the provision for a close-row cooling coil which is economical to manufacture and effective in use.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings.